Krempe

Krempe, discovering Frankenstein's fondness for alchemists in their first
interview, bursts out contemptuously, "Have you really spent your time in
studying such nonsense?" (1.2.4).
Frankenstein relates his impression of his new teacher:

M. Krempe was a little squat man, with a gruff voice and repulsive
countenance; the teacher, therefore, did not prepossess me in favour of
his doctrine. (1.2.5)

Later, though, when Frankenstein begins to apply himself to his studies,
he admits, "I found even in M. Krempe a great deal of sound sense and real
information, combined, it is true, with a repulsive physiognomy and
manners, but not on that account the less valuable" (1.3.1).